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cpython/Modules/_fileio.c

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/* Author: Daniel Stutzbach */
#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stddef.h> /* For offsetof */
/*
* Known likely problems:
*
* - Files larger then 2**32-1
* - Files with unicode filenames
* - Passing numbers greater than 2**32-1 when an integer is expected
* - Making it work on Windows and other oddball platforms
*
* To Do:
*
* - autoconfify header file inclusion
*/
#ifdef MS_WINDOWS
/* can simulate truncate with Win32 API functions; see file_truncate */
#define HAVE_FTRUNCATE
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif
typedef struct {
PyObject_HEAD
int fd;
int readable;
int writable;
int seekable; /* -1 means unknown */
PyObject *weakreflist;
} PyFileIOObject;
PyTypeObject PyFileIO_Type;
#define PyFileIO_Check(op) (PyObject_TypeCheck((op), &PyFileIO_Type))
/* Note: if this function is changed so that it can return a true value,
* then we need a separate function for __exit__
*/
static PyObject *
fileio_close(PyFileIOObject *self)
{
if (self->fd >= 0) {
int fd = self->fd;
self->fd = -1;
Py_BEGIN_ALLOW_THREADS
errno = 0;
close(fd);
Py_END_ALLOW_THREADS
if (errno < 0) {
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
}
Py_RETURN_NONE;
}
static PyObject *
fileio_new(PyTypeObject *type, PyObject *args, PyObject *kews)
{
PyFileIOObject *self;
assert(type != NULL && type->tp_alloc != NULL);
self = (PyFileIOObject *) type->tp_alloc(type, 0);
if (self != NULL) {
self->fd = -1;
self->weakreflist = NULL;
}
return (PyObject *) self;
}
/* On Unix, open will succeed for directories.
In Python, there should be no file objects referring to
directories, so we need a check. */
static int
dircheck(PyFileIOObject* self)
{
#if defined(HAVE_FSTAT) && defined(S_IFDIR) && defined(EISDIR)
struct stat buf;
if (self->fd < 0)
return 0;
if (fstat(self->fd, &buf) == 0 && S_ISDIR(buf.st_mode)) {
#ifdef HAVE_STRERROR
char *msg = strerror(EISDIR);
#else
char *msg = "Is a directory";
#endif
PyObject *exc;
PyObject *closeresult = fileio_close(self);
Py_DECREF(closeresult);
exc = PyObject_CallFunction(PyExc_IOError, "(is)",
EISDIR, msg);
PyErr_SetObject(PyExc_IOError, exc);
Py_XDECREF(exc);
return -1;
}
#endif
return 0;
}
static int
fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
{
PyFileIOObject *self = (PyFileIOObject *) oself;
static char *kwlist[] = {"file", "mode", NULL};
char *name = NULL;
char *mode = "r";
char *s;
#ifdef MS_WINDOWS
Py_UNICODE *widename = NULL;
#endif
int ret = 0;
int rwa = 0, plus = 0, append = 0;
int flags = 0;
int fd = -1;
assert(PyFileIO_Check(oself));
if (self->fd >= 0)
{
/* Have to close the existing file first. */
PyObject *closeresult = fileio_close(self);
if (closeresult == NULL)
return -1;
Py_DECREF(closeresult);
}
if (PyArg_ParseTupleAndKeywords(args, kwds, "i|s:fileio",
kwlist, &fd, &mode)) {
if (fd < 0) {
PyErr_SetString(PyExc_ValueError,
"Negative filedescriptor");
return -1;
}
}
else {
PyErr_Clear();
#ifdef Py_WIN_WIDE_FILENAMES
if (GetVersion() < 0x80000000) {
/* On NT, so wide API available */
PyObject *po;
if (PyArg_ParseTupleAndKeywords(args, kwds, "U|s:fileio",
kwlist, &po, &mode)) {
widename = PyUnicode_AS_UNICODE(po);
} else {
/* Drop the argument parsing error as narrow
strings are also valid. */
PyErr_Clear();
}
}
if (widename == NULL)
#endif
{
if (!PyArg_ParseTupleAndKeywords(args, kwds, "et|s:fileio",
kwlist,
Py_FileSystemDefaultEncoding,
&name, &mode))
goto error;
}
}
self->readable = self->writable = 0;
self->seekable = -1;
s = mode;
while (*s) {
switch (*s++) {
case 'r':
if (rwa) {
bad_mode:
PyErr_SetString(PyExc_ValueError,
"Must have exactly one of read/write/append mode");
goto error;
}
rwa = 1;
self->readable = 1;
break;
case 'w':
if (rwa)
goto bad_mode;
rwa = 1;
self->writable = 1;
flags |= O_CREAT | O_TRUNC;
break;
case 'a':
if (rwa)
goto bad_mode;
rwa = 1;
self->writable = 1;
flags |= O_CREAT;
append = 1;
break;
case '+':
if (plus)
goto bad_mode;
self->readable = self->writable = 1;
plus = 1;
break;
default:
PyErr_Format(PyExc_ValueError,
"invalid mode: %.200s", mode);
goto error;
}
}
if (!rwa)
goto bad_mode;
if (self->readable && self->writable)
flags |= O_RDWR;
else if (self->readable)
flags |= O_RDONLY;
else
flags |= O_WRONLY;
#ifdef O_BINARY
flags |= O_BINARY;
#endif
#ifdef O_APPEND
if (append)
flags |= O_APPEND;
#endif
if (fd >= 0) {
self->fd = fd;
}
else {
Py_BEGIN_ALLOW_THREADS
errno = 0;
#ifdef MS_WINDOWS
if (widename != NULL)
self->fd = _wopen(widename, flags, 0666);
else
#endif
self->fd = open(name, flags, 0666);
Py_END_ALLOW_THREADS
if (self->fd < 0 || dircheck(self) < 0) {
PyErr_SetFromErrnoWithFilename(PyExc_IOError, name);
goto error;
}
}
goto done;
error:
ret = -1;
done:
PyMem_Free(name);
return ret;
}
static void
fileio_dealloc(PyFileIOObject *self)
{
if (self->weakreflist != NULL)
PyObject_ClearWeakRefs((PyObject *) self);
if (self->fd >= 0) {
PyObject *closeresult = fileio_close(self);
if (closeresult == NULL) {
#ifdef HAVE_STRERROR
PySys_WriteStderr("close failed: [Errno %d] %s\n",
errno, strerror(errno));
#else
PySys_WriteStderr("close failed: [Errno %d]\n", errno);
#endif
} else
Py_DECREF(closeresult);
}
Py_Type(self)->tp_free((PyObject *)self);
}
static PyObject *
err_closed(void)
{
PyErr_SetString(PyExc_ValueError, "I/O operation on closed file");
return NULL;
}
static PyObject *
err_mode(char *action)
{
PyErr_Format(PyExc_ValueError, "File not open for %s", action);
return NULL;
}
static PyObject *
fileio_fileno(PyFileIOObject *self)
{
if (self->fd < 0)
return err_closed();
return PyInt_FromLong((long) self->fd);
}
static PyObject *
fileio_readable(PyFileIOObject *self)
{
if (self->fd < 0)
return err_closed();
return PyInt_FromLong((long) self->readable);
}
static PyObject *
fileio_writable(PyFileIOObject *self)
{
if (self->fd < 0)
return err_closed();
return PyInt_FromLong((long) self->writable);
}
static PyObject *
fileio_seekable(PyFileIOObject *self)
{
if (self->fd < 0)
return err_closed();
if (self->seekable < 0) {
int ret;
Py_BEGIN_ALLOW_THREADS
ret = lseek(self->fd, 0, SEEK_CUR);
Py_END_ALLOW_THREADS
if (ret < 0)
self->seekable = 0;
else
self->seekable = 1;
}
return PyBool_FromLong((long) self->seekable);
}
static PyObject *
fileio_readinto(PyFileIOObject *self, PyObject *args)
{
char *ptr;
Py_ssize_t n;
if (self->fd < 0)
return err_closed();
if (!self->readable)
return err_mode("reading");
if (!PyArg_ParseTuple(args, "w#", &ptr, &n))
return NULL;
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = read(self->fd, ptr, n);
Py_END_ALLOW_THREADS
if (n < 0) {
if (errno == EAGAIN)
Py_RETURN_NONE;
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
return PyInt_FromLong(n);
}
#define DEFAULT_BUFFER_SIZE (8*1024)
static PyObject *
fileio_readall(PyFileIOObject *self)
{
PyObject *result;
Py_ssize_t total = 0;
int n;
result = PyBytes_FromStringAndSize(NULL, DEFAULT_BUFFER_SIZE);
if (result == NULL)
return NULL;
while (1) {
Py_ssize_t newsize = total + DEFAULT_BUFFER_SIZE;
if (PyBytes_GET_SIZE(result) < newsize) {
if (PyBytes_Resize(result, newsize) < 0) {
if (total == 0) {
Py_DECREF(result);
return NULL;
}
PyErr_Clear();
break;
}
}
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = read(self->fd,
PyBytes_AS_STRING(result) + total,
newsize - total);
Py_END_ALLOW_THREADS
if (n == 0)
break;
if (n < 0) {
if (total > 0)
break;
if (errno == EAGAIN) {
Py_DECREF(result);
Py_RETURN_NONE;
}
Py_DECREF(result);
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
total += n;
}
if (PyBytes_GET_SIZE(result) > total) {
if (PyBytes_Resize(result, total) < 0) {
/* This should never happen, but just in case */
Py_DECREF(result);
return NULL;
}
}
return result;
}
static PyObject *
fileio_read(PyFileIOObject *self, PyObject *args)
{
char *ptr;
Py_ssize_t n;
Py_ssize_t size = -1;
PyObject *bytes;
if (self->fd < 0)
return err_closed();
if (!self->readable)
return err_mode("reading");
if (!PyArg_ParseTuple(args, "|i", &size))
return NULL;
if (size < 0) {
return fileio_readall(self);
}
bytes = PyBytes_FromStringAndSize(NULL, size);
if (bytes == NULL)
return NULL;
ptr = PyBytes_AsString(bytes);
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = read(self->fd, ptr, size);
Py_END_ALLOW_THREADS
if (n < 0) {
if (errno == EAGAIN)
Py_RETURN_NONE;
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
if (n != size) {
if (PyBytes_Resize(bytes, n) < 0) {
Py_DECREF(bytes);
return NULL;
}
}
return (PyObject *) bytes;
}
static PyObject *
fileio_write(PyFileIOObject *self, PyObject *args)
{
Py_ssize_t n;
char *ptr;
if (self->fd < 0)
return err_closed();
if (!self->writable)
return err_mode("writing");
if (!PyArg_ParseTuple(args, "s#", &ptr, &n))
return NULL;
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = write(self->fd, ptr, n);
Py_END_ALLOW_THREADS
if (n < 0) {
if (errno == EAGAIN)
Py_RETURN_NONE;
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
return PyInt_FromLong(n);
}
/* XXX Windows support below is likely incomplete */
#if defined(MS_WIN64) || defined(MS_WINDOWS)
typedef PY_LONG_LONG Py_off_t;
#else
typedef off_t Py_off_t;
#endif
/* Cribbed from posix_lseek() */
static PyObject *
portable_lseek(int fd, PyObject *posobj, int whence)
{
Py_off_t pos, res;
#ifdef SEEK_SET
/* Turn 0, 1, 2 into SEEK_{SET,CUR,END} */
switch (whence) {
#if SEEK_SET != 0
case 0: whence = SEEK_SET; break;
#endif
#if SEEK_CUR != 1
case 1: whence = SEEK_CUR; break;
#endif
#if SEEL_END != 2
case 2: whence = SEEK_END; break;
#endif
}
#endif /* SEEK_SET */
if (posobj == NULL)
pos = 0;
else {
#if !defined(HAVE_LARGEFILE_SUPPORT)
pos = PyInt_AsLong(posobj);
#else
pos = PyLong_Check(posobj) ?
PyLong_AsLongLong(posobj) : PyInt_AsLong(posobj);
#endif
if (PyErr_Occurred())
return NULL;
}
Py_BEGIN_ALLOW_THREADS
#if defined(MS_WIN64) || defined(MS_WINDOWS)
res = _lseeki64(fd, pos, whence);
#else
res = lseek(fd, pos, whence);
#endif
Py_END_ALLOW_THREADS
if (res < 0)
return PyErr_SetFromErrno(PyExc_IOError);
#if !defined(HAVE_LARGEFILE_SUPPORT)
return PyInt_FromLong(res);
#else
return PyLong_FromLongLong(res);
#endif
}
static PyObject *
fileio_seek(PyFileIOObject *self, PyObject *args)
{
PyObject *posobj;
int whence = 0;
if (self->fd < 0)
return err_closed();
if (!PyArg_ParseTuple(args, "O|i", &posobj, &whence))
return NULL;
return portable_lseek(self->fd, posobj, whence);
}
static PyObject *
fileio_tell(PyFileIOObject *self, PyObject *args)
{
if (self->fd < 0)
return err_closed();
return portable_lseek(self->fd, NULL, 1);
}
#ifdef HAVE_FTRUNCATE
static PyObject *
fileio_truncate(PyFileIOObject *self, PyObject *args)
{
PyObject *posobj = NULL;
Py_off_t pos;
int ret;
int fd;
fd = self->fd;
if (fd < 0)
return err_closed();
if (!self->writable)
return err_mode("writing");
if (!PyArg_ParseTuple(args, "|O", &posobj))
return NULL;
if (posobj == Py_None || posobj == NULL) {
posobj = portable_lseek(fd, NULL, 1);
if (posobj == NULL)
return NULL;
}
else {
Py_INCREF(posobj);
}
#if !defined(HAVE_LARGEFILE_SUPPORT)
pos = PyInt_AsLong(posobj);
#else
pos = PyLong_Check(posobj) ?
PyLong_AsLongLong(posobj) : PyInt_AsLong(posobj);
#endif
if (PyErr_Occurred()) {
Py_DECREF(posobj);
return NULL;
}
#ifdef MS_WINDOWS
/* MS _chsize doesn't work if newsize doesn't fit in 32 bits,
so don't even try using it. */
{
HANDLE hFile;
PyObject *pos2;
/* Have to move current pos to desired endpoint on Windows. */
errno = 0;
pos2 = portable_lseek(fd, posobj, SEEK_SET);
if (pos2 == NULL)
{
Py_DECREF(posobj);
return NULL;
}
Py_DECREF(pos2);
/* Truncate. Note that this may grow the file! */
Py_BEGIN_ALLOW_THREADS
errno = 0;
hFile = (HANDLE)_get_osfhandle(fd);
ret = hFile == (HANDLE)-1;
if (ret == 0) {
ret = SetEndOfFile(hFile) == 0;
if (ret)
errno = EACCES;
}
Py_END_ALLOW_THREADS
}
#else
Py_BEGIN_ALLOW_THREADS
errno = 0;
ret = ftruncate(fd, pos);
Py_END_ALLOW_THREADS
#endif /* !MS_WINDOWS */
if (ret != 0) {
Py_DECREF(posobj);
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
return posobj;
}
#endif
static char *
mode_string(PyFileIOObject *self)
{
if (self->readable) {
if (self->writable)
return "r+";
else
return "r";
}
else
return "w";
}
static PyObject *
fileio_repr(PyFileIOObject *self)
{
if (self->fd < 0)
return PyUnicode_FromFormat("_fileio._FileIO(-1)");
return PyUnicode_FromFormat("_fileio._FileIO(%d, '%s')",
self->fd, mode_string(self));
}
static PyObject *
fileio_isatty(PyFileIOObject *self)
{
long res;
if (self->fd < 0)
return err_closed();
Py_BEGIN_ALLOW_THREADS
res = isatty(self->fd);
Py_END_ALLOW_THREADS
return PyBool_FromLong(res);
}
PyDoc_STRVAR(fileio_doc,
"file(name: str[, mode: str]) -> file IO object\n"
"\n"
"Open a file. The mode can be 'r', 'w' or 'a' for reading (default),\n"
"writing or appending. The file will be created if it doesn't exist\n"
"when opened for writing or appending; it will be truncated when\n"
"opened for writing. Add a '+' to the mode to allow simultaneous\n"
"reading and writing.");
PyDoc_STRVAR(read_doc,
"read(size: int) -> bytes. read at most size bytes, returned as bytes.\n"
"\n"
"Only makes one system call, so less data may be returned than requested\n"
"In non-blocking mode, returns None if no data is available.\n"
"On end-of-file, returns ''.");
PyDoc_STRVAR(readall_doc,
"readall() -> bytes. read all data from the file, returned as bytes.\n"
"\n"
"In non-blocking mode, returns as much as is immediately available,\n"
"or None if no data is available. On end-of-file, returns ''.");
PyDoc_STRVAR(write_doc,
"write(b: bytes) -> int. Write bytes b to file, return number written.\n"
"\n"
"Only makes one system call, so not all of the data may be written.\n"
"The number of bytes actually written is returned.");
PyDoc_STRVAR(fileno_doc,
"fileno() -> int. \"file descriptor\".\n"
"\n"
"This is needed for lower-level file interfaces, such the fcntl module.");
PyDoc_STRVAR(seek_doc,
"seek(offset: int[, whence: int]) -> None. Move to new file position.\n"
"\n"
"Argument offset is a byte count. Optional argument whence defaults to\n"
"0 (offset from start of file, offset should be >= 0); other values are 1\n"
"(move relative to current position, positive or negative), and 2 (move\n"
"relative to end of file, usually negative, although many platforms allow\n"
"seeking beyond the end of a file)."
"\n"
"Note that not all file objects are seekable.");
#ifdef HAVE_FTRUNCATE
PyDoc_STRVAR(truncate_doc,
"truncate([size: int]) -> None. Truncate the file to at most size bytes.\n"
"\n"
"Size defaults to the current file position, as returned by tell().");
#endif
PyDoc_STRVAR(tell_doc,
"tell() -> int. Current file position");
PyDoc_STRVAR(readinto_doc,
"readinto() -> Undocumented. Don't use this; it may go away.");
PyDoc_STRVAR(close_doc,
"close() -> None. Close the file.\n"
"\n"
"A closed file cannot be used for further I/O operations. close() may be\n"
"called more than once without error. Changes the fileno to -1.");
PyDoc_STRVAR(isatty_doc,
"isatty() -> bool. True if the file is connected to a tty device.");
PyDoc_STRVAR(seekable_doc,
"seekable() -> bool. True if file supports random-access.");
PyDoc_STRVAR(readable_doc,
"readable() -> bool. True if file was opened in a read mode.");
PyDoc_STRVAR(writable_doc,
"writable() -> bool. True if file was opened in a write mode.");
static PyMethodDef fileio_methods[] = {
{"read", (PyCFunction)fileio_read, METH_VARARGS, read_doc},
{"readall", (PyCFunction)fileio_readall, METH_NOARGS, readall_doc},
{"readinto", (PyCFunction)fileio_readinto, METH_VARARGS, readinto_doc},
{"write", (PyCFunction)fileio_write, METH_VARARGS, write_doc},
{"seek", (PyCFunction)fileio_seek, METH_VARARGS, seek_doc},
{"tell", (PyCFunction)fileio_tell, METH_VARARGS, tell_doc},
#ifdef HAVE_FTRUNCATE
{"truncate", (PyCFunction)fileio_truncate, METH_VARARGS, truncate_doc},
#endif
{"close", (PyCFunction)fileio_close, METH_NOARGS, close_doc},
{"seekable", (PyCFunction)fileio_seekable, METH_NOARGS, seekable_doc},
{"readable", (PyCFunction)fileio_readable, METH_NOARGS, readable_doc},
{"writable", (PyCFunction)fileio_writable, METH_NOARGS, writable_doc},
{"fileno", (PyCFunction)fileio_fileno, METH_NOARGS, fileno_doc},
{"isatty", (PyCFunction)fileio_isatty, METH_NOARGS, isatty_doc},
{NULL, NULL} /* sentinel */
};
/* 'closed' and 'mode' are attributes for backwards compatibility reasons. */
static PyObject *
get_closed(PyFileIOObject *self, void *closure)
{
return PyBool_FromLong((long)(self->fd < 0));
}
static PyObject *
get_mode(PyFileIOObject *self, void *closure)
{
return PyUnicode_FromString(mode_string(self));
}
static PyGetSetDef fileio_getsetlist[] = {
{"closed", (getter)get_closed, NULL, "True if the file is closed"},
{"mode", (getter)get_mode, NULL, "String giving the file mode"},
{0},
};
PyTypeObject PyFileIO_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"FileIO",
sizeof(PyFileIOObject),
0,
(destructor)fileio_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_compare */
(reprfunc)fileio_repr, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
fileio_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
offsetof(PyFileIOObject, weakreflist), /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
fileio_methods, /* tp_methods */
0, /* tp_members */
fileio_getsetlist, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
fileio_init, /* tp_init */
PyType_GenericAlloc, /* tp_alloc */
fileio_new, /* tp_new */
PyObject_Del, /* tp_free */
};
static PyMethodDef module_methods[] = {
{NULL, NULL}
};
PyMODINIT_FUNC
init_fileio(void)
{
PyObject *m; /* a module object */
m = Py_InitModule3("_fileio", module_methods,
"Fast implementation of io.FileIO.");
if (m == NULL)
return;
if (PyType_Ready(&PyFileIO_Type) < 0)
return;
Py_INCREF(&PyFileIO_Type);
PyModule_AddObject(m, "_FileIO", (PyObject *) &PyFileIO_Type);
}
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